// processinfo.h

/*    Copyright 2009 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects
 *    for all of the code used other than as permitted herein. If you modify
 *    file(s) with this exception, you may extend this exception to your
 *    version of the file(s), but you are not obligated to do so. If you do not
 *    wish to do so, delete this exception statement from your version. If you
 *    delete this exception statement from all source files in the program,
 *    then also delete it in the license file.
 */

#pragma once

#include <string>

#include "mongo/platform/cstdint.h"
#include "mongo/platform/process_id.h"
#include "mongo/db/jsobj.h"

namespace mongo {

    class ProcessInfo {
    public:
        ProcessInfo( ProcessId pid = ProcessId::getCurrent() );
        ~ProcessInfo();

        /**
         * @return mbytes
         */
        int getVirtualMemorySize();

        /**
         * @return mbytes
         */
        int getResidentSize();

        /**
         * Get the type of os (e.g. Windows, Linux, Mac OS)
         */
        const std::string& getOsType() const { return sysInfo().osType; }

        /**
         * Get the os Name (e.g. Ubuntu, Gentoo, Windows Server 2008)
         */
        const std::string& getOsName() const { return sysInfo().osName; }

        /**
         * Get the os version (e.g. 10.04, 11.3.0, 6.1 (build 7600))
         */
        const std::string& getOsVersion() const { return sysInfo().osVersion; }

        /**
         * Get the cpu address size (e.g. 32, 36, 64)
         */
        unsigned getAddrSize() const { return sysInfo().addrSize; }

        /**
         * Get the total amount of system memory in MB
         */
        unsigned long long getMemSizeMB() const { return sysInfo().memSize / (1024 * 1024); }

        /**
         * Get the number of CPUs
         */
        unsigned getNumCores() const { return sysInfo().numCores; }

        /**
         * Get the system page size in bytes.
         */
        static unsigned long long getPageSize() { return systemInfo->pageSize; }

        /**
         * Get the CPU architecture (e.g. x86, x86_64)
         */
        const std::string& getArch() const { return sysInfo().cpuArch; }

        /**
         * Determine if NUMA is enabled (interleaved) for this process
         */
        bool hasNumaEnabled() const { return sysInfo().hasNuma; }

        /**
         * Determine if file zeroing is necessary for newly allocated data files.
         */
        static bool isDataFileZeroingNeeded() { return systemInfo->fileZeroNeeded;  }

        /**
         * Determine if we need to workaround slow msync performance on Illumos/Solaris
         */
        static bool preferMsyncOverFSync() { return systemInfo->preferMsyncOverFSync;  }

        /**
         * Get extra system stats
         */
        void appendSystemDetails( BSONObjBuilder& details ) const {
            details.append( StringData("extra"), sysInfo()._extraStats.copy() );
        }

        /**
         * Append platform-specific data to obj
         */
        void getExtraInfo( BSONObjBuilder& info );

        bool supported();

        static bool blockCheckSupported();

        static bool blockInMemory(const void* start);

        /**
         * @return a pointer aligned to the start of the page the provided pointer belongs to.
         *
         * NOTE requires blockCheckSupported() == true
         */
        inline static const void* alignToStartOfPage(const void* ptr) {
            return reinterpret_cast<const void*>(
                    reinterpret_cast<unsigned long long>(ptr) & ~(getPageSize() - 1));
        }

        /**
         * Sets i-th element of 'out' to non-zero if the i-th page starting from the one containing
         * 'start' is in memory.
         * The 'out' vector will be resized to fit the requested number of pages.
         * @return true on success, false otherwise
         *
         * NOTE: requires blockCheckSupported() == true
         */
        static bool pagesInMemory(const void* start, size_t numPages, std::vector<char>* out);

    private:
        /**
         * Host and operating system info.  Does not change over time.
         */
        class SystemInfo {
        public:
            std::string osType;
            std::string osName;
            std::string osVersion;
            unsigned addrSize;
            unsigned long long memSize;
            unsigned numCores;
            unsigned long long pageSize;
            std::string cpuArch;
            bool hasNuma;
            BSONObj _extraStats;

            // This is an OS specific value, which determines whether files should be zero-filled
            // at allocation time in order to avoid Microsoft KB 2731284.
            //
            bool fileZeroNeeded;

            // On non-Solaris (ie, Linux, Darwin, *BSD) kernels, prefer msync.
            // Illumos kernels do O(N) scans in memory of the page table during msync which
            // causes high CPU, Oracle Solaris 11.2 and later modified ZFS to workaround mongodb
            // Oracle Solaris Bug: 
            //  18658199 Speed up msync() on ZFS by 90000x with this one weird trick
            bool preferMsyncOverFSync;

            SystemInfo() :
                    addrSize( 0 ),
                    memSize( 0 ),
                    numCores( 0 ),
                    pageSize( 0 ),
                    hasNuma( false ),
                    fileZeroNeeded (false), 
                    preferMsyncOverFSync (true) { 
                // populate SystemInfo during construction
                collectSystemInfo();
            }
        private:
            /** Collect host system info */
            void collectSystemInfo();
        };

        ProcessId _pid;
        static mongo::mutex _sysInfoLock;

        static bool checkNumaEnabled();

        static ProcessInfo::SystemInfo* systemInfo;

        inline const SystemInfo& sysInfo() const {
            return *systemInfo;
        }

    public:
        static void initializeSystemInfo();

    };

    bool writePidFile( const std::string& path );

    void printMemInfo( const char * whereContextStr = 0 );

}
